This invention relates to a remote shut-off valve, and in particular to a valve for the remote shutting-off of a fluid such as a main water supply.
The invention is expected to find its greatest utility as a shut-off valve for the water supply to a domestic dwelling, and the following description will therefore relate primarily to such application. However, use of the invention for other liquid flows such as liquid petrochemicals, and in other applications such as the water supply to commercial and recreational premises, are not thereby excluded. Also, the invention is applicable to gas flows, i.e. it can be used to shut off the flow of, a gas along a pipeline.
The mains water supply usually enters a domestic dwelling through a single pipeline, and close to the point of entry a tap (known as a xe2x80x9cstop-cockxe2x80x9d) is typically provided so that the water supply to the dwelling can be shut-off if required, for example if there is a water leak within the dwelling. The stop-lock is usually located out of sight, and is not always easily accessible, particularly for the elderly or infirm. In addition, the stop-lock may not need to be operated for many years, and might have become seized during that time, so that it is not possible for the dwelling occupier to operate it when it is ultimately required.
It is known to provide a shut-off valve which can be fitted into the mains supply adjacent or instead of the stop-cock, which shut-off valve can be more easily operated, particularly by the elderly or infirm. In addition, certain designs are remotely operated so that the valve can be actuated from a convenient location.
One prior art device is disclosed in GB patent application 2,279,393. That document discloses an electrically-operated stop-cock which can be fitted to the mains supply pipe in addition to or instead of the manually-operated stop-cock. The electically-operated stop-cock can be actuated by the dwelling occupier from a remote location.
The device of GB 2,279,393 has the major disadvantages of being expensive and complex, due to the requirement for electrical actuation. Also, it is indicated that in the event of an electrical failure the valve will close, shutting off the water supply, but that a magnet can be used to-reopen the valve manually if desired. Clearly, it might not be desired that the water be shut off if there is a failure in the electricity supply, and the requirement to locate a suitable magnet, and then be able to open the valve manually, is likely to be extremely difficult.
Another prior device is disclosed in WO 97/05416. In that document there is provided a shut-off valve which can be actuated remotely, and which operates by water pressure alone, i.e. it requires no complex mechanical or electrical components. That document discloses a diaphragm valve located in a water supply pipeline, and which valve is normally biassed closed. When it is desired for water to flow along the pipeline (which may be connected to a tap over a domestic sink for example), the user can depress an actuator which mechanically opens a pilot valve, which in turn opens the diaphragm valve and allows water to flow along the pipeline. When the user stops depressing the actuator the pilot valve closes and the diaphragm valve subsequently closes. The device is intended to save water use by cutting off the water supply to the tap when the actuator is not being depressed, in the event that the tap is left turned on, for example.
The device of WO97/05416 also has a number of disadvantages for use as a shut-off valve, however. Thus, it is designed to fit into a pipeline adjacent an individual water outlet or tap, and is therefore normally biassed closed. The present invention, however, is directed to a stop-cock which controls the flow of all water into the building, and so is normally open. It is not practical for an shut-off valve such as that of WO97/05416 to be used for the mains supply pipeline into a building or dwelling.
Also, the device of WO97/05416 is directional, in that both the diaphragm valve and the pilot, valve must be fitted correctly into the water supply line; incorrect fitment of either component will result in the device not operating correctly, e.g. the diaphragm valve could remain closed even if the pilot valve is opened.
In addition, the water pressure within the pilot valve seeks to open the pilot valve, but this water pressure is resisted by the mechanical linkage of the actuator. If the mechanical linkage should fail, the pilot valve and hence the diaphragm valve would be biassed towards its open condition, avoiding the intended purpose of the device.
Furthermore, the inlet to the diaphragm valve communicates with the control chamber above the diaphragm by way of a number of small holes in the diaphragm. The size of those holes is critical to operation of the device. It is a recognised disadvantage of such diaphragm valves that if the holes are too large then the diaphragm valve will not open even if the pilot valve is opened, so that fluid flows from
the inlet to the outlet by way of the holes in the diaphragm and the pilot valve. The holes in the flexible diaphragm may become enlarged through successive opening and closing movements of the diaphragm, leading to premature failure of the device.
In the disclosed embodiments of the device of WO97/05416, there is a threaded connection between the valve body and the valve top; securement of the valve top is likely to distort the diaphragm which might also act to increase the size of the holes, increasing the likelihood of premature failure of the device.
The connections between the flexible fluid conduits and the rigid components of the device of WO97/05416 are by way of push-on fish-tail connectors, which are not suitable for mains water pressure supply, i.e such connectors are likely to leak at mains water pressures.
Alternative quick-release connections are known for use in mains water supply applications. Ones such connection is known as a xe2x80x9cJohn Guestxe2x80x9d connection in which the flexible fluid conduit is fitted into an opening in a rigid body and engages an O-ring seal. A resilient collet surrounds the end of the flexible conduit and is located within the recess. The formation of the collet and recess is such that attempts to pull the flexible conduit out of the recess act to increase the friction between the collet and the conduit so that the conduit is effectively retained within the collet, in sealing engagement with the O-ring. Quick-release of the connection is possible, however, in that when it is desired to remove the conduit from the recess it is necessary to press the collet into the recess as the conduit is being removed.
It is an object of the present invention to reduce or avoid the disadvantages of the devices mentioned above. It is a further object to provide a remote shut-off valve which can be quickly and easily installed into a mains water supply pipeline.
According to the present invention there is provided a remote shut-off valve comprising a diaphragm valve and a pilot valve, the diaphragm valve having an inlet, an outlet, a valve member and a valve seat, the valve member having a closed position in which it engages the seat and blocks the flow of fluid from the inlet to the outlet and an open position in which the valve member does not engage the valve seat and fluid can flow from the inlet to the outlet, a first fluid conduit connecting the inlet of the diaphragm valve to the inlet of the pilot valve and a second fluid conduit connecting the outlet of the pilot valve to the outlet of the diaphragm valve, the diaphragm valve having a control chamber, and a flow channel connecting the control chamber to the diaphragm valve inlet, characterised in that the flow channel is located within the body of the diaphragm valve.
By virtue of the flow channel being located within the body of the diaphragm valve, it is not necessary to have holes in the diaphragm itself, so that the above-mentioned disadvantages of such an arrangement are reduced or avoided.
Connecting the control chamber to the diaphragm valve inlet ensures that the diaphragm valve will be biassed closed when the pilot valve is closed, and the diaphragm valve will be open when the pilot valve is open. Since it is intended that the diaphragm valve will normally be open (and will only be shut when it is desired to close off the mains water supply pipeline to the dwelling or the like) the pilot valve normally remains open. It is an advantage of such an arrangement that whilst the pilot valve is open, fluid will flow along the fluid conduits (in addition to the flow through the diaphragm valve) and so reduce the likelihood that scale or other deposits will build up in the fluid conduits or the pilot valve.
Preferably, the diaphragm valve includes a removable cap member which provides the control chamber; preferably also a part of the fluid conduits are formed through the cap member. Desirably, the flow channel comprises a branch in the first fluid conduit within the cap member. Desirably also the periphery of the diaphragm can be clamped between the cap member and the diaphragm valve body. Such an arrangement reduces the complexity of the diaphragm valve, and in particular makes assembly easier, and also replacement of the diaphragm easier, should this become necessary. In addition, the diaphragm periphery can act as a seal between the cap member and the diaphragm valve body.
Desirably, the diaphragm valve body, cap member, pilot valve body and valve member are manufactured from plastics materials. Such materials are known to be less liable to scale formation (as might occur with some mains water supplies) than metallic components.
Preferably, part of the first and second fluid conduits are provided by respective flexible tubes secured to the diaphragm valve (and preferably to the cap member thereof) by way of xe2x80x9cquick-releasexe2x80x9d connectors. Ideally, the quick-release connectors include respective O-ring seals which can engage a part of the flexible tube and provide a seal therearound. Preferably, releasable securing means are provided to secure the flexible tubes within the respective O-ring seal. In a preferred embodiment, the releasable securing means for securing the flexible tubes to the diaphragm valve comprises a securing housing within which both of the tubes are securely retained, the housing carrying locking means to lock the housing, and therefore the flexible tubes, to the diaphragm valve.
The provision of flexible tubes providing a part of the respective fluid conduits is advantageous for remote applications, since the diapgragm valve and the pilot valve can be secured in their required or desired positions, and the flexible tubes can be manipulated as required to provide the fluid communication therebetween.
Desirably, the flexible tubes are at least partially resilient, and each is retained within the securing housing at least in part by a curved channel within which the tube is located. It will be understood that a flexible resilient tube will seek to straighten itself out into a substantially a linear configuration; forcing the tube into a curve can result in a frictional engagement retaining the tube within the channel.
Preferably, the securing housing includes a collar for each of the respective flexible tubes; preferably also, a part of the channel wall is removed at a position substantially aligned with the collar. The removed wall allows the tube to be maintained substantially linear whilst it is inserted into the required position relative to the collar; only when the tube has been correctly positioned within the collar is it necessary to curve the tube to locate this within the channel.
Preferably, the pilot valve is located within a valve housing. Preferably also, the valve housing includes a curved channel for each of the flexible tubes. Desirably, the pilot valve is removable from the housing. This arrangement permits the flexible tubes to be fitted to the pilot valve in a substantially linear configuration, or at least a configuration with shallow curvature. Only when the conduits are secured to the pilot valve is it necessary to curve each tube into its respective channel, the tendency of the tube to straighten itself out acting to retain it within the channel.